FERTILIZERS FOR MAIZE 211 



compared with the plat coiitinuously in maize without fertilizer 

 was 2,6 bushels per acre.^ 



285. Maintaining the Crop Producing Power of the Soil. — 



The use of stable manure and the rotation of crops in connec- 

 tion with stock raising are the chief means of keeping the land 

 in good condition to grow maize. Maize is not an exhaustive 

 crop because (i) it removes from the soil comparatively small 

 quantities of soil elements for food produced; (2) it produces 

 large quantities of organic matter which when fed to live-stock 

 makes large quantities of organic manure to return to the soil ; 

 (3) the intercultm-al tillage is doubtless beneficial, although this 

 has not been as fully demonstrated as the expression of Jethro 

 Tull, — "Tillage is manure," — might indicate. 



The Indiana Station^ manured for two years a series of alter- 

 nate plats which had grown maize continuously for five years 

 with fresh horse manure amounting for t^vo years to about fift}' 

 tons per acre. No manure was used before or since. During 

 twelve years the average yield was nearly ten bushels per acre 

 more on the manured than on the unmanured plats and on the 

 last year of the period was nearly five bushels greater. 



286. Influence of Organic Matter. — Stable manure is more 

 frequently applied to land intended for maize than to any other. 

 Grass and clover are usually followed by maize. One reason 

 why stable manure is found generally beneficial for maize is that 

 it supplies organic matter, which when in proper condition may 

 modify the water contend of the soil. Instances are known 

 where no influence whatever was obtained from the use of 

 large quantities of commercial fertilizers, but where the use of 

 stable manure increased the crop. The Wisconsin Station 

 found that while the total amount of water in the upper sLx feet 

 of soil was essentially equal in both manured and unmanured 



I IlL BuL 42, p. 177. 

 * Ind. buL 55, p. 29. 



